New Theory Explains How Black Holes And Neutron Stars Shine

Black holes are astronomical objects with gravitational pulls so strong that not even light can escape them, while neutron stars are stellar objects that form when a massive star collapses. The two are some of the most mysterious objects in the universe; both emitting mysterious light that makes them shine bright.

Astrophysicists believe that the reason why the celestial regions that host black holes and neutron stars shine brightly is because of high-energy radiation generated by electrons moving nearly at the speed of light. However, the exact mechanisms as to how electrons accelerate to such extreme speeds have remained a mystery.

To uncover the mystery, researchers of a new study published in The Astrophysical Journal designed supercomputer simulations to solve equations that describe the turbulence of charged particles in gas. In fact, the researchers’ simulations are considered some of the largest in the research area.

“We used the most precise technique — the particle-in-cell method — for calculating the trajectories of hundreds of billions of charged particles that self-consistently dictate the electromagnetic fields,” principal investigator Lorenzo Sironi of Columbia University said.

The simulations revealed that the electromagnetic radiation that makes black holes and neutron stars shine is a result of two major things: turbulence and magnetic reconnection. Reconnection essentially selects the particles that will be accelerated by the magnetic fields, and the particles gain most of its energy by bouncing off the turbulent fluctuations at random.

“Turbulence and magnetic reconnection — a process in which magnetic field lines tear and rapidly reconnect — conspire together to accelerate particles, boosting them to velocities that approach the speed of light,” first author Luca Comisso of Columbia University said. “It is thanks to the electric field induced by reconnection and turbulence that particles are accelerated to the most extreme energies, much higher than in the most powerful accelerators on Earth, like the Large Hadron Collider at CERN," he went on.

The stronger the magnetic field, the more rapid the acceleration of the electrons are. And, because the strong fields cause the particles to move with a curved trajectory, the acceleration results in the emission of electromagnetic radiation; thus, making the black hole or neutron star shine bright.

While the simulations provide excellent information about the extreme environments around black holes and neutron stars, it could also shed light on the understanding of how the universe functions.

That said, researchers say that there is still more work to be done, as advances in research are often the result of large collaborative work.

For the next step, the researchers are planning to compare their simulations to actual electromagnetic radiation emitted by the Crab Nebula, which happens to be the most intensely studied remnant of a supernova.